7. Golden Sun: Dark Dawn
Development begun: unclear
While the third entry in the Golden Sun series may not have actually been in development for very long, fans were waiting for the game since GS: The Lost Age hit the Game Boy Advance in 2003. Not only was it the best portable RPG ever, but it even stood up to console games in terms of length and depth. Not to mention that the ending was a cliffhanger to end all cliffhangers.
Speculation of a third game naturally took off, with rumors that it would appear on the GameCube gaining traction in 2004. Nintendo was ambiguous about whether they'd even make it, though, so it faded from the spotlight until finally being unveiled at E3 2009. Its reception wasn't all positive, as the formula seems to have staled over the interim seven years, and many considered it too easy. Still, fans were mostly happy it had happened at all.